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bpf: notify offload JITs about optimizations

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Let offload JITs know when instructions are replaced and optimized
out, so they can update their state appropriately.  The optimizations
are best effort, if JIT returns an error from any callback verifier
will stop notifying it as state may now be out of sync, but the
verifier continues making progress.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jakub Kicinski 2019-01-22 22:45:24 -08:00 committed by Alexei Starovoitov
parent 9e4c24e7ee
commit 08ca90afba
4 changed files with 53 additions and 0 deletions
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7
include/linux/bpf.h
View File

@ -268,9 +268,15 @@ struct bpf_verifier_ops {
};
struct bpf_prog_offload_ops {
/* verifier basic callbacks */
int (*insn_hook)(struct bpf_verifier_env *env,
int insn_idx, int prev_insn_idx);
int (*finalize)(struct bpf_verifier_env *env);
/* verifier optimization callbacks (called after .finalize) */
int (*replace_insn)(struct bpf_verifier_env *env, u32 off,
struct bpf_insn *insn);
int (*remove_insns)(struct bpf_verifier_env *env, u32 off, u32 cnt);
/* program management callbacks */
int (*prepare)(struct bpf_prog *prog);
int (*translate)(struct bpf_prog *prog);
void (*destroy)(struct bpf_prog *prog);
@ -283,6 +289,7 @@ struct bpf_prog_offload {
void *dev_priv;
struct list_head offloads;
bool dev_state;
bool opt_failed;
void *jited_image;
u32 jited_len;
};

5
include/linux/bpf_verifier.h
View File

@ -266,5 +266,10 @@ int bpf_prog_offload_verifier_prep(struct bpf_prog *prog);
int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env,
int insn_idx, int prev_insn_idx);
int bpf_prog_offload_finalize(struct bpf_verifier_env *env);
void
bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off,
struct bpf_insn *insn);
void
bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt);
#endif /* _LINUX_BPF_VERIFIER_H */

35
kernel/bpf/offload.c
View File

@ -173,6 +173,41 @@ int bpf_prog_offload_finalize(struct bpf_verifier_env *env)
return ret;
}
void
bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off,
struct bpf_insn *insn)
{
const struct bpf_prog_offload_ops *ops;
struct bpf_prog_offload *offload;
int ret = -EOPNOTSUPP;
down_read(&bpf_devs_lock);
offload = env->prog->aux->offload;
if (offload) {
ops = offload->offdev->ops;
if (!offload->opt_failed && ops->replace_insn)
ret = ops->replace_insn(env, off, insn);
offload->opt_failed |= ret;
}
up_read(&bpf_devs_lock);
}
void
bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt)
{
struct bpf_prog_offload *offload;
int ret = -EOPNOTSUPP;
down_read(&bpf_devs_lock);
offload = env->prog->aux->offload;
if (offload) {
if (!offload->opt_failed && offload->offdev->ops->remove_insns)
ret = offload->offdev->ops->remove_insns(env, off, cnt);
offload->opt_failed |= ret;
}
up_read(&bpf_devs_lock);
}
static void __bpf_prog_offload_destroy(struct bpf_prog *prog)
{
struct bpf_prog_offload *offload = prog->aux->offload;

6
kernel/bpf/verifier.c
View File

@ -6558,6 +6558,9 @@ static int verifier_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt)
unsigned int orig_prog_len = env->prog->len;
int err;
if (bpf_prog_is_dev_bound(env->prog->aux))
bpf_prog_offload_remove_insns(env, off, cnt);
err = bpf_remove_insns(env->prog, off, cnt);
if (err)
return err;
@ -6632,6 +6635,9 @@ static void opt_hard_wire_dead_code_branches(struct bpf_verifier_env *env)
else
continue;
if (bpf_prog_is_dev_bound(env->prog->aux))
bpf_prog_offload_replace_insn(env, i, &ja);
memcpy(insn, &ja, sizeof(ja));
}
}